Bovine papillomavirus type 1 induces skin tumors when it is transmitted through the germ line of transgenic mice. The two frequent skin pathologies which arise -- abnormal skin and protuberant tumors -- will be analyzed in order to assess several notable characteristics of tumorigenesis: the slow appearance of abnormalities, at sites prone to irritation and wounding; the inactivity of the BPV genome in normal skin tissue and its activation in all abnormal conditions; and the apparent progression in the transformed phenotype of affected dermal fibroblasts. Using tissue biopsies and primary cultures of dermal fibroblasts from normal transgenic skin, abnormal skin, and protuberant tumors, we will characterize: 1) the four apparent states of dermal fibroblasts, so as to establish criteria with which to distinguish them on molecular and cellular levels; 2) the nature of the activation mechanism for BPV in normal skin, as to whether its silence results from cis or trans effects; 3) the possible role of the immune system in slow oncogenesis; and 4) tumor progression, both as it occurs naturally in these mice, as well as in response to attempts to accelerate it. Two mutant BPV genomes will be tested in new lines of transgenic mice, to assess the necessity of extrachromosomal replication and the 31% "late" region in tumorigenesis. The BPV E5, E6, and E2 ORFs will be widely expressed as hybrid genes in transgenic mice, in order to assess the tissue specificity of their activities. The genomes of human papilloma viruses type 5 and type 18 will be established in lines of transgenic mice, in order to develop mouse models for the human cancers associated with these tumor viruses. We will characterize the ability of HPV-5 and HPV-18 to heritably induce tumor formation in transgenic mice, and analyze the types of abnormalities which arise, with respect to the expression of the HPV oncogenes, the histological character of the affected cells, and their cellular phenotypes. Additional experiments will seek to induce and/or accelerate tumorigenesis with specific agents, which will include carcinogens, tumor promoters, radiation and retroviruses expressing oncogenes such as Ha-ras and c-myc. The E6/E7 and E5 regions will be expressed under broad specificity promoters in transgenic mice, so as to address the penetrance (of specificity) of these oncogenes.